Generating station incremental cost computers, and the like



July 1, 1958 J. H. STARR ETAT. 298433 GENERATING STATION TNCREMENTAL OOST COMPUTERS, AND THE: LIKE Filed June 15, 1955 2 sheets-Sheet 1 July 1, 1958 1H. STARR ETAL 2,841,331

GENERATING STATION INCREMENTAL COST COMPUTERS, AND THE LIKE 4 Filed June 13, 1955 2 Sheets-Sheet 2 United States Patent O GENERATING STATIGN INCREMENTAL COST COMPUTERS, AND THE LIKE James H. Starr, La Grange, and Robert A. Clark, Jr., River Forest, lll., and Millard C. Westrate, Jackson, Mich.

Application June 13, i955, Serial No. 515,162

17 Claims. (Cl. 23S-61) This invention concerns itself with improvementsY in generating station incremental cost computers, and the like. The incremental cost of a power generating unit varies with the output of such unit, and such incremental cost may be shown by an incremental cost curve relating incremental cost rate to output of the generating unit over the permissible range of loadings of such unit. It has been shown that when a number of power generating units contribute to supply a total power requirement the most economical division of such total power requirement between such contributing units is that division under which the incremental costs of all of the units are equal for the powers to be supplied by such units. If the total power requirement is that power to be delivered by a power station having a number of generating units then the division of such total generating station power among the units of lsuch station in service at any given time should be that division under which the incremental costs of such several generating units in service are the same. lf the total power requirement is that power which is to be delivered by a network to a number of loads connected to the network at different points, which network is fed by power from a number of generating stations, then the incremental costs of all such generating stations should be the same, by proper division of total power requirements between all such stations, taking proper account of the network losses and the portion of such losses which must be carried by each generating station as a part 'of the load on such station.

It thus becomes important to have available accurate and reliable data as to the true incremental rate for each generating station, over the range of power supplied by such station, and such data must be based on presently existing operating costs and plant conditions. Such data should take into account the incremental rates of the several power generating units of such station in use at the time. Having in hand dataor curves showing the incremental rate of each generating station, or the incremental rate for each unit of such sation, for various power outputs within the acceptable power range of such station or unit, the operator is able to determine the optimum division of total power requirements between the various contributors to lsuch total. He may determine such division of power on the basis of experience; or he may feed the information so gained into a calculating table by which further determinations are made which take into proper account network losses and other factors which iniluence the determination of the complete solution of the problem of division of total power requirements between a number of contributors to such network.

The'present invention concerns itself with the provision of an incremental cost computer by which the incremental cost of a generating station may be determined within a very small error, very quickly, and on the basis of presently existing operating costs and conditions of the plants elements. Broadly stated, the prime object 2,841,331 Patented July 1, 1958 of the present invention is to provide a continuous or rapidy produced indication of the corrected incremental cost of each generating unit based on presently existing fuel costs and operating conditions. Such information may then be used as a basis for despatch of power into the network, or for other purposes.

More specifically the present disclosures are directed to provision of means to -give a continuous indication of incremental cost for each station or for each unit within a station under the then existing internal station conditions, including correction not only for cost of fuel in cents per M B. t. u., but also including correction for substantially all factors which materially aiect the losses incident to conversion from `chemical to electrical energy, and the amount of heat rejected to the cooling water for the condensers. Such indicated station incremental cost does not include any adjustment or correction for incremental transmission losses since the load or power supplied by each contributing station must include the portion of the total network losses which should be carried by such ystation at the load division finally determined as being the most economical, and thus becomes a portion of the load actually carried by such contributing station. The means whereby the station incremental costs for the various contributors to the total requirements of a given network and its loads, may be used and coordinated to determine the optimum division of total power requirements, taking proper account of the effects of network losses, is disclosed elsewhere. The generating station incremental cost data or indications obtained by use of cost computers to which the present invention relates may be fed as input data to the means or devices which are used to determine the optimum division of the total power requirements, as well as for making studies and decisions for other purposes.

The following statement will :outline various underlying principles aifecting incremental cost ratesof the generating station and/or its units, and the determination of such incremental rates:

An electric power company buys energy in the form of fuel and sells energy in electrical form. The lower the cost of fuel for a given hour of operation, the greater the operating proiit. The conversion of the energy in the fuel into electrical form is accompanied by the loss of energy through ineiciencies in the conversion equipment and rejection of energy in accordance with established thermodynamic principles. The anticipated losses in conversion and through rejection are computed at the time the plant is constructed and these computations are confirmed by acceptance tests. From these computations and tests, curves are prepared showing the fuel input corresponding to cach value of electrical output over the range of operation contemplated. These curves may be corrected from time to time as subsequent test data become available although no attempt is normally undertaken to make such corrections -on an hour to hour, or day to day basis. Having such fuel input-power output curves for each contributor to the network, and knowing the cost of fuel at each power contributor,.the curves may be re-plotted or corrected, or a correction factor may be introduced into the data, to show actual present variation of total cost of fuel per hour against total power contributed by the generating station. Incremental oost curves which are rst derivatives of the foregoing curves, may then be plotted showing actual l present values and variations of incremental cost of'each Y generators. -Any cross-connections which'are provided applied to incremental vcost rate curves based on previousV test's such as acceptance tests, is much simplified. 1 We shall therefore consider the application of the features ofV our present nventionras vso applied to a single plant section` to determine the actual present incremental cost Y rate curve,'or'the correction factors to be applied to previously obtained empirical curves.

Having obtained such presently accuratecurves'the total loading beingecarried Vby the station should be divided between the twoor more plant sections onrsuch a ratio that they all operate at loadssuchV that their incremental cost rates are-equal. Furthermore, when `such Vdivision of total plant power output between its sections has Vbeen determined, the incremental cost rate of Vsuch plant as a whole lwill'be Ythat incremental-cost rate at which'the cost ratesof -thefsevera'l plant sections are also equal'to each other. Y

Consider a steam-electric generating station unit comprising a vsingle turbine driven electric generator with a f single -boiler and related equipment. During the design and installation period a heat balance diagram is constru'ctedY based 4Von manufacturers data and computa-y tions-which corresponds to the most economicaloperationof such .combined plant. This diagram is normally based on those values vof throttle temperature and pressurel for lwhich the turbine; was designed, and on the exhaust pressure on which suchV design was based, From thisheat balance, Ysometimes after confirmation Vby tests, is constructed a fuel inputvs. power output curve, and by application of the'proper fuel cost rate,the curve may be -fuel inputV cost vs. power output. The derivative of this curve with `respect to power output 'is'the incremental powercostrvs. output curve. The fuel Vinput vs.V power output Ycurve isfnormally either a straight line or slightly concave upward, withl a positive intercept at zero power output. `,Frequently theV curve will yhave one or more points iof discontinuity depending on the type of govern-V ing employed. The incremental fuel cost vs. power output lcurve will be somewhatsimilarin shape, and may be represented by a series of straight line segments, each 'of suitable'slope Vand intercept. Y 4 Y As 'disclosed .in the co-pending application of the undersigned, James'I-I; Starr and Robert A. Clark, Jr., Serial No. 483,452, filed January 2l, 1955, for Calculating Table, and the Like, a voltage may be developed which is yproportional tokincremental fuel cost by passing acur'rent proportional to power output through a resistor of Yappropriate value in series with a xed voltage. The slope ofY the voltage-current relation is determinedby the value of the resistor, and the intercept is equal tothe value of theY series fixed voltage. By selection of the proper resistance and fixed Vvoltage values the correct relationship may be produced so that the values of the incremental fuel rates corresponding to changing power values ,may

be simulated; and byV application of a proper correction factor, such voltage indication may be used to simulate the incremental'fuel cost rate, If, due to discontinuities in the form of theincremental cost curve, there are a series of line segments required Vfor correct Vsimulation of the incremental cost rate over the desiredv range of power 1 output values, theV appropriate resistance and series voltage values are inserted through the operation of microswitches actuated by Vservo-type instrument responding to v net power output ofthe unit in question. The selection in the foregoing arrangement is of course dependent'on the shape and actual values indicated by the curve which such arrangement simulates,l Accordingly, such arrangement may be .arranged to simulate either the incremental cost curve based on the designs of the unit, or on acceptance or other tests. or if the fuel cost changes,or if othersignificant conditions affecting the form or absolute valuesof the incremental cost rate curve change, it is evident that provisions must be made to effect corrections or` introduce correction factors Whichwill V'result in bringing the form and values of the curve into harmony with the actualities then existing.

' Before proceeding to an explanation of the means which we have herein disclosed for effecting corrections to the incremental cost rate curve for the unit in question, the

. following further explorationsare in order:

Each line segment of the curve relating'fuel cost tov output may be represented by an expression in thelform (l) `$/hr.'=C(albP- :P2), where C=costof fuel in cents per B.Y t. u.;

:net power output; and a, b and c='appropriate coeicients.

Then the corresponding line segment in the incremental fuel cost vs. outputrcurveis (2) dr'sfnrg/dpgcwrzcp) Since the foregoing relationships have been based on the incremental cost curve 'without corrections for pres#V ently existingv departures Yfrom the conditions of operation and plant condition on which such curvewas predicated it now remains to examine vtherc'onditions which affect the present values of that curve, and tov show how corrections may be made Vwhichwill produce incremental cost values based on the present conditions.

The plant operating conditions are notjconstant throughout'the .normal Vyear of operation."V Changes in fuel analysis and water content, air temperaturqandY quantity, barometric pressure, cooling water ltemperature, condition of the furnace, boiler, turbine, condenser, or auxiliary equipment may loccur Yfront-day tov day `or hour to hour 'whichV more Vor less materially'affect 'the Vare provided Vwhich continuously indicate the present the amount of heat released inthe'furnace to produce one unit -of net power-at'the buses. The effects of such` changes-on theincremental cost of Vpowervmust thereforel be explored. 1

First, a' testmaybeV applied to determinewhether or not the incremental cost curve as originally vdetermined and plotted represents, at 'the present time,- the actual present incremental cost rate. Y This will indicate the need or Votherwise of application of Va correction.L Let -it be assumed that the Afuelf'cost vs.-output,and'the incremental Vfuel cost vs., output curves :had been correctly plotted for the 4Voperating conditions forwhich the equipment was designed.Y `Letitlalso be assumed that instruments rate of fuel'consumptionexpressedV in $/hr.,fand the net power output, after subtracting any auxiliary gpower use, in kw. Then, Vat any instant these two readings'fprovide the coordinates of *a single point which maybe plotted on the fuel cost vs. Voutput curve. If. all plant conditions are identical with-thosel assumed in kthe `computation of this curve, the pointlwillli'e on the curvegrotherwiseeit probably will not; A The fact that the point does ,lije on the curve is conclusive .'evidencerthat 'the original 'curvefis still a correct representation of the present operating .conf` From this it may be assumed. that the originalV Vincremental costys.;

ditions.

u V.output vcurve iszalso presently-k accurate. w, v

Next we consider'in what manner 'thejcurve of 'incremental fuel costvsVolrltputA :be alteredjif thejpoint mentioned the precedingparagraph idees-not lie onV the4V curve which was plotted for .the :operating conditions.

If the operating `'conditions change;

for which the equipment was designed. It is correct to state that each dollar of fuel burned releases a denite amount of heat in B. t. u., and further that of this amount of heat released, a denite fraction appears as net energy at the busbars available for sale. If the factor `C in the preceding Equations 1 and 2 shall be re-dened, not as cents per B. t. u. total heat content of the fuel, but rather as cents per B. t. u. net available energy content of the fuel, as hereinafter discussed, then the preceding equations provide a simple answer to the question of how the curve of incremental fuel cost vs. output should be altered to correctly show the incremental cost on the basis of presently existing operating conditions. Following out this analysis the reasoning below applies:

Consider that the dollars fuel input vs. kilowatts salable power output curve indicates that with an output P1 the cost of fuel per hour is R1 and the incremental fuel cost curve for that same output, P1 indicates that the incremental fuel cost is S1, and at a specific time the fuel cost meter indicates the cost of fuel, not as R1 but as R1 at an output P1, then the incremental cost is not S1 but S1, so that This simple equation is valid only if the coefficients a, b and c in Equations 1 and 2 remain constant, that is, these coeihcients are the same at the present time as they were at the time of the acceptance tests or are the same as they were assumed to be when the incremental cost curve or the fuel input vs. power output curve was calculated and plotted from the design characteristics referred to earlier herein. As a matter of fact these coecients probably do not remain constant or are not the same under the conditions then and now existing. However, the variation is slight in comparison with the quantity C as re-defined above. To illustrate this fact consider the following:

Make the assumption that all conditions remain just as they were assumed to be in making the original computation of the input fuel cost vs. output and incremental fuel cost vs. output curves, except that there is a substantial increase in the moisture associated with each dollar cost of the fuel. This moisture is vaporized in the furnace, and the latent heat of vaporization is no longer available to heat the fluid within the boiler. As re-defined C is the cost of the net available heat in the fuel, and as there is less net available heat due to the necessity for using part of the gross heat to vaporize the water, the value of C increases; that is to say, there are now more cents per net B. t. u. input. The ratio between the original and the present value of C is established by the ratio between the ideal and the actual present rate of fuel feed, the former being known from the original curve and the latter from the fuel rate meter, hereinafter to be referred to. There is no apparent variation in the coefficients a, b or c. Actually, there must be more pounds of fuel fed to the furnace to maintain the same output after the water content is increased, and these added pounds require more air for combustion, burning to more gaseous products. These greater volume gaseous products must move at higher velocity through the boiler. Therefore they are in contact with the boiler surfaces for a reduced interval. This means that less of the heat contained in these gases is absorbed by the boiler and that therefore some or all of the coefficients a, b and c do actually change. However, the actual change in velocity is slight and the effect on the efficiency of heat transfer is also slight.

The error ensuing from the assumption that the coefficients remain constant is insignificant in comparison with the error which would result from assuming that the water in the fuel had no effect on the incremental cost.

Similar reasoning may be applied to a very large number. ofvariable factors which affect the overall heat rate Y, of a steam-electric generating unit. In some instances the reasoning is less justified than in others but in all cases the error resulting from the vimplied assumptionv that the coefficients a, b and c remain substantially constant, and that only C varies is acceptably small in contrast to the conventional presently accepted assumption that incremental cost is always that indicated by the incremental cost vs. output curve calculated on the basis of idealized operating conditions. One example to sustain this proposition is the following:

lf the cooling water is warmer than required for the nominal back pressure for which the turbine is designed, the exhaust pressure is higher and there is lessenergy available for conversion into mechanical form (and thence to electrical energy). In this case the assumption that incremental rate varies in direct proportionV to fuel input is substantially correct. But if the cooling water is at a lower temperature than the standard condition the back pressure is lower and the steam is expanded to a greater volume than the final stage blading is designed to handle eiciently at rated load. 'Ihe efficiency drops rather sharply under this condition and the incremental rate found by multiplying the nominal incremental rate (that assumed from the acceptance tests or from the data previously referred to) by the fuel input ratio is over-optimistic. Even so, the error introduced by the assumption that the incremental rate varies in direct proportion to fuel input is small when compared to the error prevailing when no correction factor is applied as is the conventional presently accepted practice.

Considered fundamentally, our invention comprises the provision of means to determine the present incremental cost rate of energy now being delivered by the generating unit at the output now being supplied by such generating unit, by determining a correction factor to be applied to the ideal,incremental rate at such output, such ideal incremental rate being based on design calculations, or on. acceptance or other tests, such correction factor being applied to said ideal incremental cost rate for such output. More specifically, our invention includes the provisionwith such ratio determining means, of further means to apply such ratio to said ideal incremental cost rate at such output.

In carrying into practice our invention we provide the following elements of equipment, or equivalent elements and functions thereof: 1

First: A fuel metering unit which measures the fuel input to the furnaces of furnaces and furnace equipment, which supply steam to the generating unit in question. Such fuel metering equipment may be either a continuous indicating unit showing or indicating continuously an indication based on rate of fuel consumption; or it may be an instrument giving its indications as average rates based on short time intervals of operation. The indications of such fuel metering equipment may be given directly in B. t. u./hr., since the incremental cost rate is directly influenced by the total B. t. u. input, all of which input including all losses, must be paid for. Since the rate of B. t. u. input depends on the actual rate of fuel input multiplied by the B. t. u. content of the fuel per unit volume or per unit weight, provision is made, either in the B. t. u. meter, or by a proper correction factor appliedto the weight or volume rate, for causing the meter indication to be given in B. t. u./hr. The metering equipment must of course be of type suitable for the kind of fuel being used, whether gas, liquid, or solid. We shall speak further of this B. t. u. metering equipment hereinafter. Conveniently, also provision is made for giving the B. t. u./ hr. meter indication as a D. C. potential whose value is proportional to such B. t. u./ hr. indication. The reasons for this preference will appear hereinafter.

Second: We also provide means to continuously meter the net power Output of the generating equipment in question. Conveniently this means may comprise a Thermoverter of the type put. out by TheBristol Comaniram ,pany-ofwaterbury, Connecticut, and known kas Ther-V moveften Modei w-s7s, anadis'crosed in Letti-.fis Patn'taof-..the;United States, Nos. 1,407,147and 1,456,591.

Suchdevices are V`a1soclescribedin Sales Data Sheet, No.. 220, of said Bristo'n Company, dated MarchV 1..1940.

Weldonnot, however, intend` toI limit ourselves to such metering devices; but they are well adapted to use in connectioriV with otherY elements of vequipment `hereinafter referred .tog This -isubecause,famong other things, such Bristol devices-.deliver'a D.C..potentialgproportional to the power being measured, and with a veryV small time lag of the indicationgas values-of power change;

(Third: We also provide means to give an` indication proportional tothe B. t. ut/hrfinput-at the netpower Voutput now being delivered by the generating unit, but

underrthe ideal-conditions whichwe have previously referred to.Y` Those are.the design characteristics of the,

plant, or the calculatedresults of the acceptance or other tests.Y Conveniently, this third means takes the form of a biased potentiometer .which will deliver a D. C. potential proportional to 'the B.,t. u./hr. fuel input required byY the ggeneratingunit under the design conditions, Vor the acceptance vor other tests, and normally used in plotting the heat-input vs. power-outputcurve previously referredV housed to produce values of voltage. drop proportionaly tothe incremental heat rate vat the now existing output but ,when operating under therideal conditions. Since by Suchgmeans the incremental heat rate maybe indicated by s uchp'otential'this typeV ofV unitis well adapted for usein connection with. the elements of means previ- Y ously mentioned, Vas well as other such elements of fmeans This fourth means thus delivers a potential which is proportional to the incremental heat rate at the presently existingV generating unit output andA under the ideal conditions previously referred to. The indication corresponding to this potential must then be corrected by a ratiowhich is'found by comparing the B. t. u`./hr. at the presently existing generating output, under presently existingV conditions, with the B. t. u./hr. at the presently 'existingoutpun but under the ideal conditions.

Fifth: We also provide-means controlled by the presentlyrexisting net power output to shift the third means to a position corresponding to the presently existing net power output so that third means shall deliver its D. C. potential in amount-controlled by the presently existing net power output Thus the D. C. potential deiivered by said third meansr shall represent the ideal heat rate at thc value of net power output presently existing. This fth means also adjusts an A. C. potential to a value which is proportionalto the net power output presently existing, which'A. C. potential is used in the operation of the fourth means.` This fth means also adjusts the group of `series-connected voltage-'resistor elements of the fourth means to a condition corresponding to the presently existing net power outputV so that the voltage drop across said voltage-resistor elements Ashall represent Vthe incremental heat rate of the generating unitat the net power output now existing, but for'the ideal conditions,'already referred to.-` l'his adjustment conveniently takes the form of selectionV of that voltage-resistor element which will produce a voltage drop proportional tothe incremental heat rate'at the presently existing output of the generating unitV whenoperating under-the ideal conditions. This fifth means conveniently takes thel form of a servo-motor tov thei net, Vpower output of the generating unit.

Y .t driven element which is moved to a position corresponding Such fifth means may; conveniently include anv instrument of the. A

'ing cost of the fuel used in Idollars/ B. Vt'. u.

type vof the fMoseleyD C. voltmeter, rModel; ZO-Seriesri; produced by thev F. L. YMoseley Co., ofA Pasadena,

California, and described in Bulletin No. 7 of that corn-V pany, and dated March 1954. Itconyeniently prnakeqsgitsI setting lby Acomparison of the D. C. potential' delivered bythe Thermoverter of. the Vsecondrrneans Ywith aDfreferencevoltage.

Sixth: lWe also provide means controlled by the.V Y

potential which is adjusted by thel fifth means to a yvalue,

proportional Vto the net power output presently existing,Y i to adjust the current. in theY fourth means arrdkflowing`vv through the series-connected voltage-resistorelements of;

the fourthk means, as selected bythe ifthlmeans,V toa; value proportional to the Vnet power outputV of ,thegenerating unit. Thus the fourth means is brought toa condition such that the potential across the so-selected series-connected voltage-resistor element shall represent: the incremental heat rate under the ideal conditions and for the generating unit output presently existing. -Thissixth means also conveniently takes theform of a motor driven element in an instrument of said MoseleyD. C voltmeter type. comparison of the drop of potential across a fixed resistor throughwhich flowfs'the current ofthe selected serieskconnected voltage-resistor element, with the A. C. potential which represents the presently existing output of the.

generating unit, as adjusted by the fth means.V Y

f Seventh: We also provide means to compare the actual presently metered. heat rate inrB. t. u./hr. input, for the .presentlybeing deliveredV power output (theirst means), withthe ideal heat rateinB. t.V u./hr. for the presently .being delivered Lpower-output (the :third means), and to produceanadjustment of a variable v ratio elementV to a value which equals the ratio of VYthe ideal heat rate 'in B. t.V u./hr. as calculated from the designs or determined from the acceptance tests,.at-the present output, compared Vto the presentheat rate-in B. t. u./hr. for the present output. This seventh means also conveniently takes the form of a servo-'motor drivenelement moved to a position in Awhich a'conditionofV balance is produced based on the presently existing value of such ratio. Suchv servo-motor driven Ielement comprises a portion of an instrument of the Moseley type previously'referred to. `Such servo-driven Yelement, unit conveniently makes its finding of ratio by compari-- son of the voltage representing the ideal conditionk with the lvoltage representing presently existing heatfratep both-on the basis of the presently existing netpower output ofthe generating'unit. 'Y

Eighth: We alsoy provide means which applies the correction ratio determined by the seventh means', top/the iinding of the incremental heat rate under the ideal conditions, for the presently existing generating unitroutput,

as represented by an A. C. potential, to produce anotherY` Such other A. C. potential is then pro- A. C. potential. portional to the incremental heat rate for the presently existing generating unit output, and'under the presently existing B. t. u./hr. -as determinedA by the rst means'.- This application ofsaid ratio to the ideal incremental heat rate Vis conveniently produced by varying the ratio of the primary and secondary windings of a transformer,Y

such variation being effected-'by the movement of the f motor driven element of the seventh meansrabove referred to'.

Ninth: We alsok provideV means to apply toY the cor-H rected incremental'heat rate, vas indicatedV by the eighth'. means, a multiplying factor ybased on the presently exist- This'multiplying factor conveniently takes the form ofV a variable ratio transformer which may vbe manually or otherwise set kto position corresponding to the present cost: of theV heat in dollars per unit B. t. u., or in other selected` measure of costs. i,

- We doinot intendto limit ourselves to. kspecific (forms of .the various elementsof -referredm `ahovigiY It conveniently takes its setting byY 9 but we contemplate the use of any element of equipment capable of producing the operation defined as being produced by such element of means, except as we may limit ourselves in the claims to follow. However, the following further comments respecting the form and characteristics of the first means are here in order:

As an example of a fuel metering unit for use in the first means when the fuel is a gas, the so-called Linder'-v man type meter may be used with pointer position automatically corrected for actual pressure and temperature. This pointer may then be connected to the slider of a potentiometer in such way that such slider assumes a position to include a fraction of the whole potentiometer resistance proportional to the rate of gas flow. A manually adjustable element may be provided to adjust.y a voltage to an amount proportional to the heat content of the gas in B. t. u. per standard cubic foot, and this sti-adjusted voltage may be impressed across the complete potentiometer. Under these conditions the voltage across the part of the resistance will be proportional to the B. t. u./hr. consumption. Such an arrangement is illustrated hereinafter.

If the fuel is a liquid a suitable meter may be inserted in the fuel supply line at a point where it will meter the fuel actually delivered to the furnaces. A Connersville type meter measures the volume by revolutions of a shaft, and the rate of fuel feed by rate of such shaft rotations. Any small inaccuracy in the meter. ing of this unit can be disregarded since the rate of fuel supply as metered by this unit is used in establishing a ratio between actual and ideal fuel consumption values or B. t. u. rates based thereon. Rather slow rotational speeds of the meters shaft may be converted into proportional voltage values in conventional manner. One method to do this consists in providing means to cause the shaft rotation to produce a specific number of electrical contacts (per revolution), and providing means to count the number of contacts in a stated time interval, say one minute. Such counting may be done by use of a three electrode vacuum tube which isy normally biased to cut-off, applying the pulses produced by the contacts to the grid of the tube. At each such pulse the tube becomes conducting for a very short interval of time, and at each such short conducting interval the tube passes a short charging pulse of current'from a source of xed potential to a condenser. The condenser charge is allowed to leak off at a known rate over a bleeder resistor. The average voltage remaining on the condenser at conclusion of the stated time interval will be proportional to the number of pulses delivered by the meter shaft rotations, and thus also proportional to the liquid flow in G. P. M. By manually adjusting the potential of the fixed source of potential proportional to the B. t. u. per gallon of liquid, the average condenser potential becomes proportional to the B. t. u. per minute or hour heating value of the fuel metered.

If the fuel is powdered coal the rate' of flow to the burner may be metered by an impeller located in the pipe conveying the coal to the burners. The conversion of the rate of rotation of the impellcr shaft to B. t. u./hr. may be produced by an arrangement similar to that stated above with respect to the metering of liquid fuel.

Such arrangements as those above briey described for the metering of both liquid and powdered fuel are illustrated hereinafter. and shall illustrate such metering arrangements for the fuel input only by way of illustration, and without any intention of limiting the features of our present invention thereto, except as we may so limit ourselves in the claims to follow. l

lt is here noted that under conventional generating station practice the control of the rate of fuel ow to the burners is effected by the load being carried by the generator equipment corresponding thereto. It is Well recognized that a great deal of heat is stored in the furnace We have thus briefly describedv '10 walls and proximate structural elements. During an ex tended interval when the load is substantially constant these walls and structural elements attain a steady temperature condition, with storage of a corresponding amount of heat in B. t. u. When the load changes,

vfor example, when it drops, the rate of fuel flow is auto# matically reduced to a value less than that needed to sustain the required heat supply for such reduced load; and such reduced rate of fuel supply or feed is continued for an interval during which the deficiency in rate of B. t. u. supplied by the incoming fuel is made up byl reduction of the temperature of the furnace walls and proximate structural elements, such reduction in tem` perature being accompanied, of course by surrender of B. t. u. to the water contained in the boiler, principally. After such interval of too great a reduction in rate of fuel feedsaid rate is raised to that value which will meet the steady requirements imposed by the reduced load demand. This assumes that there has been no further change in the load demand during such interval of attaining a new condition of balance.

It is accordingly evident that if the elements of the present invention, and the meter or indicator by which the corrected incremental heat rate or the corrected cost per hour is one which immediately responds to changes based on the instantaneous changes in rate of fuel feed, such indicating meter will give incorrect indications during intervals when the rate of fuel feed is being changed, and for intervals of rather indefinite duration thereafter,

and until the new condition of balance has been attained.V

In many cases such intervals needed to regain a condition of balance are small, and when a meter is provided which immediately responds to all changes is used, its

-indications may be disregarded during such transition intervals.

When the meter which indicates the actual incremental heat rate is a graphic or recording instrument, it is evident that changes in such rate as indicated on the chart of such an instrument will be in the form of slanting portions of the graph connecting substantially straight graph portions corresponding to steady conditions of operation. The rate of change of fuel feed will then be reflected in the steepness of slant of such connecting portions of such a graph. It will also be seen that when the rate of change of fuel feed is small corresponding to a gradual change in the net power output, the slanting portions of the graph will correctly redect the incremental heat rates over the interval of such change. If, however, the rate of change of output and corresponding rate of change of fuel feed is too great for a correct instantaneous indication of the incremental heat rate, such fact will be evidenced by a slant of the graph which is steeper than a prescribed degree of slant; and such too steep slanting portions of the graph may be disregarded.

Alternatively, we contemplate the provision at a suitable portion of the equipment, as for example, between the ninth means of the indicating meter which shows the incremental cost rate based on the incremental heat rate, of a suitable form of integrating circuit so that the final or indicating metery or instrument will give its indication on the average incremental rate for, say, the last minute or the last five minutes. We contemplate the provision of such means in connection with the equip t ashaving their respective servomotors connected tothe- Vtion that it delivers the potential representing the 'B. t. u./

@sanear Y T1 Y elements l ofthe means, which they; adjust, such show-T ingpsubeing-'bythe broken lines; 'e .Y 1 Y;

,Afligure 2 shows schematically aY gasmetering arrange? ment complying with thre'requirernentsr for such arneter-4 ing-unitras'previously disclosed herein;`

.p Figure 3 shows schematically a liquid metering4 arrangementV complying with the requirements for such ai metering; unit as previously disclosed herein;

^ at V14`and 15. AThesefunction to .deliver their indications on'the basis `of presently existingperformance.Y The third means' isshown at.. 16. This unit` comprises a biased potentiometer whose'iesistance element, and D. C. current connections are so arranged that as the sliding' contact 17 is shifted over the resistance element 18 to-different positions the potential between the terminals 19 and 20 is proportionalto the B. t. lu./hr. input yunder the ideal .con-n ditions, foreach adjusted position of such sliding contact. vIt will be presently shown that vsuch'sliding contact Vis caused to assume positions 'corresponding to various'net. outputs as measured by the second means, 13; andthe arrangement `of this potentiometer-of theV third` means,V 16, is such 'that for each such position of thersliding contact 17, the potential delivered `between the lines 19 and 20 is a true representation of the B. t. u V/hr. input under the` ideal conditions, and `for theY same net power output as cor-responds to suchrposition of ythe sliding contact. Under'vthe foregoing conditions and. specifications it is evident that, since both of the potentials,'that between the liners 11 and 12,V and that between the lines V19 vandY 20, represent B. t. yu./hr. conditions yfor the same net power output (the lpotential .l1-12 corresponding to presently existing conditions, andthe potential 19-7-29 corresponding to the ideal'conditions), vthese twoY potentials maybe 4compared and a ratio established which'may be'called the correo tion ratio Yor factor, to be applied to the ideal incremental lheat rate'corresponding to thatv net power out- :put in order to determine thecorrected or presently existing .incremental heat rate. of that net power .output. We shallpresently disclose how this -comparison is automatically effected, and the desired ratio determined, andy how that so-determined ratio is then automatically applied to otherV units of the ensemble to produce therdesired end result.

The fifth means is shown at `It conveniently corn-Y prises such a device as the Moseley unit already referredV to, and includes theVservo-motor element 22 which drives thefollower 23 Vto a position such that the potential between the lines 14 and 15 (which corresponds to the ,netV power output), shall balance a portionof the potential delivered by the D. C. reference voltage element 24, atv which point such follower is arrested and held.' This follower drives the sliding contact 17 Yalready referredito",V toa position which thus corresponds .to the net power outf put, such drive being effected Vby the connect-ion 25. By this arrangement the third means is brought to such'posi'- hr. corresponding to the netV power output presently exist-i ing, but such B. t. u./hr. simulation is based on-the Videal conditions .instead of the presently existing conditions. The

fifth means also effects certain other adjustments presently to be explained.

The seventh 4means is shown v'at 26. It is Valso .con-Y veniently a unit vof the Moseley type,.inclluding the servomotor element 27 ,which drivesj the follower4 28` toY a balance condition position. j SaidV follower operates over thejpotentiometer element 29 whichni's V4connectedQaerossi thelinesgll. and KV12 and' therefore said potentiometer is subjected;-betweenthe 'pointsY ofjconnection ofthe lines 1,'1-and 12`to it, to the potential which corresponds'to the presently existing 'B.- t.u./hr. for the Vnetpower `output now vlbeing/ delivered. Usually that presently existing B151; u./hr.- will be greater than the B.Y t. u./hr under the ideal;-conditions, and accordingly, the sliding contact 30l which is moved'by Vthe follower 28 will usually .travel between the pointsof'connection ofthe lines 11 and 12 to such potentiometer4 29. The sliding contact 17 of the third means connects by the line to the seventh means, .Y I

as shown, andthe line 19 connects to the line 11, so that the servo-motor 27 will come to rest and be held with Ythe sliding contact '30at la position such that therpo'rtion of the potentiometer betweenV the sliding contact .and the line `19 produces a potential lbetween said sliding contact 3i) and the line 19feq-ual to the potential being delivered 'by the, thirdrrfmeans. Thus the arresting and holding position of Ythe sliding contact 30 and the follower 28 coro responds to the gratiol of the B. At. u./hr. underthe idealV conditions of operation comparedkto'the BQ t. u./ hr. presently ekisting, both for the net power output now beingV delivered by the .generating unit, Thus the follower 28 may be and is u sed to shift other elements, presently to bei explained, tozpositions corresponding to that ratio.l That ratio is `the correction factorV previously referred to. Y

The fourth Ymeansris shown at 352.V This unit is so constructed-that it can be caused to give an indication, in 'thexforinofV Va. potential, preferably'A. C., proportional tothe incrementalheat Vrate of the generating unit then delivering its o utput, which incremental heat rate corresponds to thev outputthen. ybeing delivered Iby such Vgenerating unit, but which incrementalheat rate is that determinedi'funrder the Yideal conditions. Those ideal conditions lare eitherthe determined incremental heat rate foi-,.such'generating unit-'based on the specifications and designs, or on theV acceptance or other tests as already explained.. Thus, said Vvfourth means, v32, delivers a potential .proportional to the incremental heat rate ofthe generating VYunit in operation, based on the id-eal conditions, andat the outputbeing delivered by-such unit'. This soldete'rmined incremental heat vrate (potential) may .thenV be subjected to the correction factor referred to in the previous paragraph, to determinerthe corresponding and true'incremental -heat rate of such generating unit, under4 the output now being Y presently existing conditions, and at delivered by such generating unit..

Thisfourth means includes atleast one, series-con-y nected voltage-.resistor sectionV 33 corresponding to the generating, unit foi-which correction of incremental heat Y rate is to v.beV determined appliedV to YtheV ideal increnientlvhreat rate .forsuchrgenerating unit.Y `In'vFigure l wefhavefshownthree `of these sections, designated asY 339'., 33E, and.336,;,respectivelyin We shalipresently `ex,- plain the reasonffor providing and illustrating more than one suchV Vseries-connected voltage-resistor section Y for 'the generating.u'nitl'in question; 4Each 1of these sectionsV includes=a-transformer 3.4 having its-primary 35 supplied with a lxed fA. C. potential a, and its secondary 36 tappedggrnegelemenn of this imitare designated by Y corresponding .identilication,numerals, but lwith thefsuf-V fixes ag ffband ,c, respectively, as shown.) Each of i these sections also includes an adjustable resistor 37-` The adjustable resistor Vand the Vtap of the secondary of each sectionare f placed .in seriesfby the connections 38. The,v

busbars. or .terminal `lines 39 and 4t) are provided, and the yslidingcontacts 41 of'all of theadjustable resistors are.V connectedito the line 40,V The'closed ends of theV n tapped secondaries of the transformers are connectedV to thev line 39 with microswitches 42 included in'such connections, so that :any selected series-connected -voltage-resistor may Ibeconnected to the line 39 lby closing the proper .microswitch t Next zwei provide aV source of A. C. of which the -potsntialpmay bei-made proportional with@ Output 110Wv 13 being delivered by the generating Iunit now in operation. Conveniently such a source comprises a transformer 43 provided with the primary 44 which is supplied with a xed potential A. C. rIhe secondary 45 of such transformer is tapped, and the sliding contact 46 may be moved to various tap positions so that lthe voltage delivered between the lines 47 and 48 may be adjusted to the tapped position value. This sliding contact 46 is connected to the follower element 23 of the servcmotor element 21 of the -tifth means, so that such sliding contact is brought and retained at position corresponding to the output now being delivered by the generating unit. Such connection is eiected by the line 49 in Figure 1. Thus the total potential between the lines 47 and 48 is proportional to the output now being delivered by the generating unit.

The current flowing in the circuit closed by the microswitch (one of the group 42a, 42b and 42), and which current lflows through the corresponding series-connected voltage-resistor section 33a, 33b or 33C as the case may be, is to be brought to a value proportional to the output now being delivered by the generating unit. That current through such section flows between the lines 39 and 40. A fixed resistor of small value, 51, and :comprising a shunt, is included in the line 39. The sixth means, 52, conveniently in the form of a Moseley unit of the type which has already been referred to, has one terminal connected to the line 39 at one end of the shunt 51, by the line 53, and its other terminal is connected by the line 54 to one end of the secondary 45 of the transformer 43. By this arrangement the drop across the shunt, produced proportionately to the current flowing through the line 39, and therefore through the seriesconnected voltage-resistor element selected by the microswitcb, is balanced against the active portion of the secondary 45, or Nice versa, so that the servo-motor of this sixth means is brought to rest and retained at position of the follower element 62 corresponding to the net output being delivered by the generating unit in question. The drive of the current through the circuit which in- Cludes the lines 39 and 40 and the selected series-connected voltage-resistor section, is Iproduced by an adjustable source of A. C. This includes the transformer 58 Whose primary 59 is fed a fixed potential A. C. The secondary 60 of this transformer is tapped. The closed end of this secondary is connected to the line 39. The sliding contact 6l of this tapped secondary is connected to the line 40. This sliding contact is connected to the follower 62 of the servo-motor of the sixth means. Thus, at the same time that the current flowing through the shunt 51 (and thus also through the series-connected voltage-resistor section) is brought to a value to simulate the output being delivered by the generating unit, the transformer 58 is caused to deliver to the circuit that amount of drive potential needed to produce such current value.

yIt is here noted that such potential (being the potential between the lines 39 and 41)) is a measure of the incremental heat rate then existing for the generating unit then in operation, and at the load then being carried by such unit.

As stated in the earlier portion of this specification, the incremental fuel input vs. power output curve is normally either a straight line or slightly concave upward, with a positive intercept at zero power output; and that frequently the curve will have one or more points of discontinuity depending on the type of governing employed. We have also pointed out that the incremental fuel cost (and incremental heat rate) vs. power output curve may be represented by a series of straight line segments, each of suitable slope and intercept. It is here noted that this latter form of delineating the curve may be used even when the curve is non-straight, since such a curve may be closely approximated by a series of consecutive short straight lines of successively steeper slopes as the output increases. Therefore to delineate the close appr'oxirn'aJ tion of the curve, whether a true curve or a straight line, or a series of straight lines or curves which are noncontinuous and are connected by points of discontinuity, use may be made lof groups of series-connected voltageresistor sections such as illustrated in Figure l at 33B, 33h and 33's. The voltage element 34 of each section is then adjusted to deliver a voltage to simulate the positive (or negative) value of the intercept at the zero position; and the resistance element 37 of such section has its contact 41 set to position such that the Variation of drop (potential) over such section, with variation of current (power simulation) produces a slope corresponding to the slope of the incremental rate line being simulated by such section 33. When several of these sections are needed or provided to simulate successive portions of the incremental rate curve such sections 33 may be brought successively into circuit in 'the unit 32 (fourth means), by `closing the proper microswitches in turn, opening the non-used microswitches so that only one section 33 will be in use at a time.

In Figure l we have indicated, by the lines 63, 64, 65 and 66 driving connections from the servo-motor of the unit 2l, or from a power output control element actuated by the output of the generating unit, whereby as the generator output changes so that a dierent section of the incremental rate curve is to be simulated, the previous microswitch will be cut out of service and the proper one v will be brought into service to connect the proper section 33 across the lines 39 and 40. By this means the fourth means is made to give its simulations over whatever power output range is needed for the generating unit in question.

Next we consider the eighth means previously defined. This unit serves to apply the correction factor to the incremental heat rate Value as determined by the fourth means just described. That correction factor is determined and indicated by the follower 28 of the seventh means already described. We provide a transformer 67 having a tapped primary 68, and a secondary 69. One end of the primary is connected to the line 4t?, and the line 39 connects to the movable contact 70 which engages the taps of the primary. This movable contact 70 is driven to position corresponding to the position of the follower 2S, by the connection 7l, so that the ratio of transformation between the primary and secondary of such transformer is brought to equality with the value of the correction factor. Accordingly, the potential delivered by the secondary 69 to the lines 72 and 73 is equal to the incremental heat rate indicated by the fourth means, corrected to presently existing conditions by the value of the correction factor.

It is now noted that the incremental heat rate thus delivered and simulated by the potential between the lines 72 and 73 is in B. t. u./hr. If it be desired to automatically produce and deliver an indication of that incremental rate in terms of incremental fuel cost, use may be made of the unit ninth means, shown in Figure l, and previously dened herein. This unit comprises the transformer 74 having its primary 75 connected across the lines 72 and 73 so that said primary is subjected to a potential which simulates the lcorrected incremental heat rate on the basis of presently existing conditions. One end of the secondary 76 of this transformer is connected to a line 77, and the secondary is tapped. The slidable contact 78 which engages such taps is then connected to the line 79. Thus the potential delivered between the lines 77 and 79 is the incremental heat rate under presently existing conditions, corrected by a factor which is the transforming ratio of the transformer 74. That ratio may be adjusted to simulate the cost of the heat in dollars or other units, so that the potential delivered between the lines 77 and 79 is a simulation of the incremental cost rate under presently existing conditions, and at the power output now being delivered.

In Figure l we have shownr'schematically at 80. an inintegrating circuit unit of such characteristics that the indication given by the pointer 81 is the average cost rate for a predetermined interval oftime, such as the'last minute or the last iive minutes of the operation. We do not deem it necessary to show in detail the form or elements of such circuit unit as the same may be of a presently known conventional type capable of producing and delivering to the pointer actuating elements, asignal which shall be of value proportional t-o the average of the quan-VV tity integrated over the interval of time.

In the foregoing disclosures we have included all of the elements and functions needed to determine and indicate the actual incremental cost of power delivered by Y the generating unit in question under present operating conditions and at the power output now being delivered. Specifically these elements of means include the means to determine the heat rate per kw./hr. under ideal condi tions, and means to determine the ratio of ideal heat rate to present heat rate. This is true as shown below:

The unit fifth means, V, a gives an indication of the present output of the generator for which purpose its follower 2'3 may move a pointer 84 in comparison to a scale 85. Said scale may be graduated to show'heat rate per kw./hr. under the ideal conditions, and said scale will in such case have its Vmarking properly spaced and designatedto show and indicate theV heat rate per kW./hr. Thus this instrument will provide, by its direct indication,

the heat rate perk kw./hr. at the output now being delivered by the generating unit in question. Y Y

The unit seventh means, VII, gives an indication of the ratio of ideal heat rate vs. present heat rate. For

this purpose the follower 28 may move a pointer S6 in comparison to aV scaler37. Said scale may be graduated to show ratio of ideal heat rate to present heat rate, and said scale willY have its markings properly spaced and designated to show suchV ratio.

By dividing the reading shown by the pointer 84 on the i scale 85 by the reading shown by the pointer 86 on theV scale 87 the heat rate per YkwJhr. under present operat- 'ling conditions is obtained. Thus (4) Heat rate per kw./hr. (present) equals heat rate per kw./hr. (ideal)/ratio of ideal heat rate to present heat rate. Y

By'applying the present cost of Vfuel per B. t. u. to the heat yrate perVkw/hr. obtained by Equation 4, we may immediately obtain the present cost rate per kW./ hr. in dollars. It is frequently desirable to determine the amount of this cost rate under present operating conditions and present Vcost of fuel per B. t. u. As shown above, the present disclosures provide the means to obtain this important information very quickly, and by a simple arithmetical operation from readings ofthe two instruments of the fifth means andthe seventh means. This feature and .objective constitute an important portion of our present invention.

In Figure 2 we have shown schematically a form ofY fuel metering arrangement to give an indication of the, B. t. u./hr. input of heat when the fuel is gas. In ythis figure We have shown a gas-metering deviceV 88 Ysuch as a gas iiow. We also provide a potentiometer V9 rsupplied with a fixed potentialV fromV the lines 94 and 95. TheY movable contact 96 of this potentiometerV may bek manually adjusted to'position to correspond torheat content'of the gas in B.-t. u. per standard cubic` foot, as shown vby i the pointer 97-'in comparison to the Vscale98. The line 94 (being one end of the potentiometer 93) connects to one end of the potentiometer 92, andthe movable contact 96 of the potentiometer 93 `connects by the line 99 `to 'Y the free end of the potentiometer 92; Underthis Varrangement the potential between the line 94 and the` movable contact 91 will be proportional to the B. t. u./h`r. Y

gas fuel consumption. The pointer'89`i's shown as connected to the Vmovable contact 91 by the connection 100.

In the'arrang'ement shown schematically inV Figure .3 provision is Vmade for determining and giving `an indica*- tion of B. t. u./'hr. when the'fuel is a liquid such as fuel oil. In this case the fuel meter is shown at 101 with the v Yinlet and outlet 'connections at 102. and 103, respectively;

As anexample of such a liquid meter'we may mention the Connersville type of meter. This instrument is provided with a shaft 104 which rotates proportionately to volume of liquid passing through the meterjbutusually the rate of shaft rotation is rather low. Accordingly, in Figure 3 we have shown the speed increasing connection fromv the shaft 104 to anothershaft '105, comprising'the wheel 106V carried by the shaft 104 and driving a smaller pulley 107 carried by the shaft 105 to drive thejsame at increased speed, by the chain connection' 108. The shaft carries a disk 109 having a number of contact points 110, the disk being connected to the line 111 of an electrical circuit. The three Yelectrode tube 112 has its grid V113 connected to the brush 114 which is engaged by the contacts as therdisk rotates. The tube 112 is normally biased for cut-off but each time the grid is electrified byV engagement of one of the contacts 110 with the brush 114 the tube is made conducting for a short interval. Y

A condenser 114E is connected to a fixed D. C. 'poten-Y tial such as the battery 115, under control of the tube 112 so that eachV time the grid is electriiied by one of the contactsV 110 a .charge is added to the condenser. bleeder resistor 116 is connected across this condenser so that leakage constantly occurs. The lines 117 Vand 118,

connected to ythe condenser, are brought to the voltmeter` 119 under control of the timing .device such as a clockV 120, provided with means to establish the circuit to the voltmeter at equally timed intervals, suchas each minute.

These circuit closings would bejfor short intervals,flong enough to give correct voltage readings, but not long enough to materially affect the calibration of the system,

on the basis of the leakage through the bleeder re-V sistor 116. v

The voltage delivered by the battery 115 is made ad- Vjustable by shift of the connection 121 from theline 118 to the proper potential point of the battery. By adjusting the potential delivered by the battery to a value proportional to the B.'t. u. per gallon of the metered fuel, the

average `condenser potential, shown by the meter v1 19 becomes proportional to the B. t. u./min. ofthe'fuelow. Conveniently, the meter 119 has its pointer'122 read in connection with the scale 123, which scale may VVthen be calibrated to read directly rate readings.

In the arrangement shown schematically kin Figurex4 provision is made for determining and giving Van indica' tion of B. t. u./hr. when the fuel is powdered coal orV other tine material of solid nature. This arrangement is` similar to that shown in Figure '3 for the case ofliquid fuel, and accordingly we have identified various of the elements shown in Figure 4 by the'same numerals as have beenused in connection with Figure 3,` but using the y suix (1. In the present case however,-the.powdered fuel is fed through the meteringtube 124 byan impellerV 125 carried by the shaft 126, the fuel entering the tube' through the connection `127 and being delivered tothe:

inrB. t. u.`/min. or other-B. t. u.V

nearest 17 furnace through the connection 12S. The shaft 126 may be driven by the motor 29 at speed controlled by the controller 130 by which the rate of fuel delivery is controlled.

Connected to the shaft lZo is the transmission unit ll having the drive member 133 which drives the member 133 at increased speed through the chain and sprocket drive shown in the iigure, or other convenient form of drive at fixed ratio of speeds. The member i339 carries the contacts llila which engage the brush lilla to deliver the short impulses in manner and for purposes functions sirnilar to those already explained in connection with the showing of Figure 3. lt is not believed necessary to repeat those functions and purposes in detail here; but it is noted that the reading of the scale E235 at the location of the pointer 122i would be in t. u./ min. or other B. t. u. rate values, depending on the potential delivered to the line USR and according to the setting of the adjustable connection lila to the source of D. C., such as the battery lSa.

It is noted that the generating unit is heat energy driven. For example, the prime mover may be steam driven, and either turbine or reciprocating type, or other; or such prime mover may bc of the internal combustion type, either two or four cycle, either diesel or other. in any case we have disclosed means to determine the heat rate input to such prime mover, and have made other provisions for determination of the present incremental heat rate at presently existing power output of the heat energy driven generating unit; and have aiso disclosed herein and have provided the means to compare the present heat rate with the ideal heat rate and to determine the ratio between said heat rates, and give an indication of such ratio.

We claim:

l. Means to determine the present incremental heat rate of a heat energy driven generating unit at presently existing net power output of said generating unit, comprising means to determine the present rate of heat energy supply to said unit and including rate of heat energy supply indicating means responsive to the present rate of energy supply, means to determine the present net power output of said generating unit and including net power output indicating means responsive to the present net power output of said generating unit to give an indication proportional to the present net power output, means to determine power output values corresponding to present net power output values under predetermined operating conditions of said generating unit and including means to give indications which are proportional to present net power output values under said predetermined operating conditions, operative connections between the aforementioned net power output response indicating means and the last mentioned determining means effective to cause the indication giving means of said last mentioned determining means to give an indication which corresponds to present net power output, means to determine the rate ot heat energy supplied to said generating unit at the present net power output and under predetermined operconditions of said generating unit, including means ive an indication of said rate of heat energy supplied ative connections between the means which gives indications which are proportional to present net power output values under the said predetermined operating conditions, and the last mentioned means to determine the rate of heat energy supplied to the generating unit, eiective to cause the indication giving means last mentioned to indicato proportionately to present net power output under said predetermined operating conditions, all said means including, means to determine and give an indication corresponding to the ratio of said indicated present rate of heat energy supply to said generating unit compared to said indicated rate of heat energy supunit under said predetermined op uating conditions of said generating unit, means to give an indication of the incremental heat rate of said generating unit under said predetermined operating conditions of said generating unit and at the present net power output, said incremental heat rate indicating means including at least one current carrying impedance unit, means to deliver current through said impedance unit and to vary said current, operative connections between the net power output indicating means which gives an indication proportional to the present net power output, and the means which delivers and varies current through the impedance unit, effective to produce a current value through said impedance unit which is proportional to the value of Ithe net power output, to produce a potential across said impedance unit corresponding to the present incremental heat rate of the generating unit, means to produce a second potential proportional to the irst mentioned potential, means to vary the ratio between both of said potentials, and operative connections between the ratio determining and indicating means aforesaid, and the means which varies the ratio between the potentials, effective to cause the ratio between the potential to vary proportionately to the indication of the ratio between the present heat rate of heat energy supply and the rate of heat energy supply under the predetermined operating conditions of the generating unit.

2. Means as defined in claim l, together with means to multiply the value of Said second potential by a factor which is proportional to the present unit cost of the heat nergy supplied to said generating unit.

3. Means as defined in claim 2, wherein said multiplying means includes means which is adjustable to selected values of said factor corresponding to selected unit costs of `the heat energy supplied to said generating unit.

4. Means as defined in claim l, wherein the heat energy supplied to said generating unit comprises solid fuel, and wherein the means to determine the present rate of heat energy supply to said generating unit includes means to determine and give an indication of the rate of supply of said solid fuel to said generating unit., means to give an indication of a fctor value corresponding to the net heat e'- -gy prot iced by said solid fuel per unit of such fuel under present operating conditions, and wherein. the means to determine and give the indication of the present pl" to said generating rate of heat energy supply to said generating unit includes means to multiply said indication of the rate of supply of said solid fuel to said generating unit multiplied by the indication which corresponds to the value of said factor.

5. Means as defined in claim l, wherein the heat energy supplied to said generating unit comprises liquid fuel, and wherein the means to determine the present rate of heat energy supply to said generating unit includes -i eans to determine and give an indication of the rate of supply said liquid fuel to said generating unit, means to give an indication of a factor value corresponding to the net heat energy produced by said liquid fuel per unit of such fuel under present operating conditions, and wherein the means to determine and give the indication of the present rate of heat energy supply to said generating unit includes means to multiply said indication of the rate of supply of said liquid fuel to said generating unit multiplied by the indication which corresponds to the value of said factor.

6. Means as defined in claim l, wherein the heat energy supplied to said generating unit comprises gaseous fuel, and wherein the means to determine the present rate of heat energy supply to said generating unit includes means to determine and give an indication of the quantity rate of supply of said gaseous fuel to said generating unit, means to give an indication of a factor value corresponding to the net heat energy produced oy said gaseous fuel per unit of such fuel under present operating conditions,

.vhereiu the means to determine and given an indica- 19 tionrof the present rate of heat energy supply to said generating unit includes means to multiply said indication f` the, quantity rateofttsu'pply .of` said gaseous fuel to said generating unit multiplied by the indication which corespondso the value of said factor.

7. Means todete'rmine and give an indication-of the ratio ofthe present'heat rate of a. heat energy Vdriven generatingV unit at present'power output in comparison toV the heat rate offsaid generating Vunit under predetermined operating conditions and at present power output,

' comprising meansto determine the present rate of heat Venergy supply to said unitY and including rate of heat energy supply indicating means responsive to the present rate of heat energy supply, means to determine the presentY netpower output of Ysaid generating unit and including netpower output indicating means responsive to the .present net power output of said generating unit to give angindicatio'n proportional to the present net power output, means to determine power output vvalues correspondingrto present netV power outputY Values under predetermined. operating conditions of said generating unit and Vincluding means togiveV indications which are proportional to present netpower output values under said predetermined operating conditions, operative connections between'the aforementioned net power output response vindicating means and the lastmentioned determining means efectiverto cause the indication giving means of said last mentioned. determining means to give an indication which corresponds rto present net power output, means to determine kthe rate of heat energy supplied to said generating unitV at present net power outsenaat put and under predetermined operating conditions of Y said generating unit including means to give an indication of said rate of heat'energy supplied to Vsaid generating unit at the present net power output and under said predetermined operating conditions, operative connections between the means which gives indications which are proportional to present net power output Values under the said predetermined operating t-co'nditions, and the last mentioned means to determineV the rate of heat energy supplied to the generating unit, effective to cause the indication giving means last mentioned to indicate proportionately to present net power output under saidV predetermined operatingconditions, all said'm-eans including, means Ato determine and give an indication corresponding to theV ratio of said indicated present rate of'heat energy supply to said generating unit at present power output compared to saidindicated rate `of heat energy supply to said generating unit under said predetermined operating conditions of said generating unit and at present power output.

8. Means ask dened in claim 7, wherein said means to determine and give an indication ofthe net power output of said generating unit includes means to give an Yindication of the heat rate per unit of power per hour under said predetermined operating conditions..

9. Means as dened in claim 7, wherein the heat en-Y ergyY supplied to said generating unit comprises solid fuel, and wherein themeans to determine and'give theindication of the present rate of heat energy supply to saidV generating unitrincludes means to determine and give an indication of the rate of supply of said solidkfuel to said generating unit, means Vto give an indication of a factor t value corresponding to the net heat energy produced by said solid fuel per unit of such fuel under present operating conditions,V and wherein the means to determine and give the indication ofthe present rate of heat energy supply to said generating unit includes means' to multiply said indicationof the rate of supply of said solid fuel to said generating unit multiplied by the `indication which corresponds to the value of said factor. y Y

' 10. Means as Ydefined in claim 7, wherein the heat energy `supplied to said generating unit comprises liquid fuel, and wherein the means to determine and give the indication of the present rate of heat energy supply to said gen- Y .72o l Y erating unit includes means to determine and cation of the rate ofsupply of. saidliquidfuel,to..saidY generating unit', means to give Van indication of a factor,

value corresponding to the net heat energy produced-by said liquid fuel `per unitof such fuel under present yoperating conditions, and wherein the means Vto determine and give the indication of the presentrate ofheat energy sup-V ply to said generating unit includes means to multiply said indication of the rate of supply of said liquid fuel to said generating unit multiplied bythe indication which corresponds to the value of said factor. Y Y' Y 1l. Means as defined in claim ,7, wherein the heat energy supplied to said generating unitrcomprises gaseous, fuel, and wherein the means to determine andgive the indication of the present rate of heat energy supply to said generating unit includes means to determine andgive anY indication Yof the quantity rate of supply of said gaseous fuel to said generating unit, means to give an indication of a factor valueV corresponding to thenet heat Y energy produced by said gaseous fuel per unit of such fuel under present operating conditions, and wherein the means to determine and give an rindication of the present rate of heat energy supply to said'generating unit includes means to multiply said indication of the quantity rate of supply of said gaseous fuel to said generating unit multi'- plied by the indication which corresponds to the value ofV said factor. Y v y l2. Means to determine the present incrementall heat rate of a heat energy driven generating unit at presently existing net power output of said generating unit, comprising means to determine the present rate ofA heat energy supply to said unit, indicating'means responsive to said determining means, Vmeans to determine the net power output of said generating unit, indicating means responsive to said determining means, means intermediate between the present rate of Aheat energy supply determining means and the net power output deter-mining means, including means to determinev arcorrected value of rate of heat energy supply Vcorresponding to presentpower output values under predetermined operating conditions for a selected range of net power output values,- indicating means responsive to such correctedtvalue of heat energy supply'determining means, operative `connections between the corrected value of the rate of heat energy supply, de'- `termining means and the net poweroutput'indicating means, and between the corrected value of rate of heat energy supply determining means and the present rate of heat energyesupply indicating means operative to cause the indicating means of the corrected value determining means to give a response indication corresponding'to rate ofheat energyrsupply for present net power output'un'der saidlpredetermined operating conditions, means to determine Ythe ratio of the present rate of'heat energy supply to said generating unit compared to the rate of heat energy supply to said generating unit under said predei termined operating conditions, indicating'means responsive to said determining means,r operative'connections between said ratio determining means andY said corrected value rate of heat energy supply indicating meanstand between said ratio Vdetermining means and said presentV rate of.Y heat energy supply indicating means effective to cause the indicating means of' said ratio determiningvr mental heat rate determining means and thernet power output indicating means effective to cause the incremental` heat rate indicating means to Agive an indication of in-.

cremental heat rate at present net power output Vunder said predetermined operating conditions, ratio applyingmeans including input value elements to receive an input value and output value elements to deliver an output value, and means to produce a selected ratio between the input value applied to the input value elements and the output value delivered at the output value elements, connections between the incremental heat rate indicating means and the input value elements of said ratio applying means, and connections between the ratio indicating means of the ratio determining means rst mentioned, and the means which produces a selected ratio between the input value and the output value of the ratio applying means second mentioned, eiective to cause the output value delivered by the output value elements to correspond to the incremental heat rate of said generating unit at present net power output and under present operating conditions.

13. Means as defined in claim 12, together with unit cost applying means to produce a second output value which is proportional to unit costs of the heat units of said incremental rate output value, comprising a variable ratio unit having input value elements and output unit cost value elements, and including means to produce output unit cost values proportional to the input values, and means to vary the ratio of the proportion produced by said variable ratio unit, together with operative connections between the output value elements of the means which produces a selected ratio above dened and the input value elements of the unit cost applying means.

14. Means as defined in claim 12, wherein the means to give an indication of said incremental heat rate is electrical, and wherein the indication of incremental heat rate at present net power output under said predetermined operating `conditions comprises a potential of which the value is proportional to the value of said incremental heat rate.

15. Means as defined in claim 14, wherein the ratio applying means is electrical and is provided with electrical input value terminals and with electrical output value terminals, and wherein the means to produce a selected ratio between the input value and the output value comprises 22 means to vary the voltage ratio between the input value terminals and the output value terminals.

16. Means as dened in claim 15, together with unit cost applying means to produce a second output value which is proportional to unit costs of the heat units of said incremental rate output value, comprising a variable ratio unit having input value elements and output unit cost value elements, and including means to produce output unit cost values proportional to the input values, and means to vary the ratio of the proportion produced by said variable ratio unit, together with operative connections between the output value elements of the means which produces a selected ratio above dened and the input value elements of the unit cost applying means.

17. Means as deiined in claim 16, wherein the unit cost applying means is electrical and is provided with electrical input value terminals and with electrical output value terminals, and wherein the cost applying means includes means to produce a potential between the output value terminals proportional to the potential across the input value terminals, and wherein the ratio between the potential across the input terminals compared to the potential between the output terminals is variable to correspond to selected unit costs of the heat units.

References Cited in the tile of this patent UNTED STATES PATENTS 2,301,470 Starr Nov. lO, 1942 2,454,520 Moore Nov. 23, 1948 2,523,453 Starr Sept. 26, 1950 2,613,237 Starr Oct. 7, 1952 2,656,977 Cummings Oct. 27, 1953 OTHER REFERENCES Co-ordination of fuel cost and transmission loss by use of the network analyzer to determine plant loading schedules (George, Page, and Ward) AIEE technical paper 49-242, September 1949. 

